Belt filter press with improved belt washer assembly

ABSTRACT

A belt filter press for deliquifying a material comprises two endless filter belts disposed adjacent each other so that a portion of the belts travel together and converge towards one another and between which a material is progressively compressed, and a belt washer for cleaning the belt of residual material, wherein the belt washer has at least one wiper holder and at least one belt wiper, wherein the at least one belt wiper is disposed against a first surface of one of the belts and removably retained thereagainst by the at least one wiper holder.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 60/287,895, filed May 1, 2001.

BACKGROUND OF INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to belt filter presses for removing liquid from a mixture of liquid and solid material. In one aspect, the invention relates to an improved belt washing apparatus for a belt filter press.

[0004] 2. Description of the Preferred Embodiment

[0005] Belt filter presses are utilized to remove liquid from a mixture of liquid and solid material, leaving a relatively dry, solid “cake” for disposal or further processing. The belt filter press comprises a frame and an assembly of rollers that support and drive an upper continuous belt and a lower continuous belt that are in operable communication with each other. The belts are permeable to allow the extrusion of the liquid therethrough. The mixture is first placed on the lower belt, then “sandwiched” between the upper and lower belts. The belts and the retained mixture then pass through a wedge section where the mixture is evenly distributed between the belts, and an initial volume of liquid is removed. The belts then pass through a series of progressively smaller diameter rollers where the retained mixture is compressed for further liquid removal. The belts are then separated and the dry “cake” is removed from the belts, generally by a scraping apparatus. The belts are then washed to remove any remaining cake, after which the process is repeated. The liquids from the extrusion and belt washing processes are collected for disposal.

[0006] Belt washers are used to clean the residual cake from the belts. These belt washers typically utilize scrapers to assist in the removal of the residue and any wash water adhering to the belts. The scrapers are typically fixedly mounted in the belt washers, necessitating a shutdown of the filter press when the scrapers must be maintained or replaced.

SUMMARY OF INVENTION

[0007] The invention comprises a belt washer assembly for a belt filter press for removing liquid from a mixture of liquid and solid material. The belt filter press comprises two endless filter belts disposed adjacent each other so that a portion of the belts travel together and converge towards one another and move together in a compression zone where material is compressed, and a belt washer for cleaning one of the belts of residual material. The belt washer has at least one wiper holder and at least one belt wiper, wherein the at least one belt wiper is disposed against a first surface of one of the belts and removably retained thereagainst by the at least one wiper holder. The at least one wiper holder is a clip and the at least one belt wiper is slidably retained in the clip. The at least one belt wiper is made of rubber or soft polyethylene. At least one scraper is disposed against a second surface of one of the belts opposite the at least one belt wiper, and the at least one scraper presses the belt against the at least one belt wiper. In one embodiment, the at least one belt wiper comprises a plurality of belt wipers, and each belt wiper is disposed from the first belt wiper in the direction of belt travel. In another embodiment, the belt washer is provided with a first pair of belt wipers and a second pair of belt wipers, with a sprayer disposed therebetween. In yet another embodiment, the belt washer is provided with a plurality of scrapers equal to the number of belt wipers.

BRIEF DESCRIPTION OF DRAWINGS

[0008] In the drawings:

[0009]FIG. 1 is a side elevational view of a schematic of a belt filter press comprising a curved wedge section, primary and secondary rollers, and a belt washer assembly according to the invention.

[0010]FIG. 2 is an exploded perspective view of the belt washer assembly of the belt filter press of FIG. 1.

[0011]FIG. 3 is a sectional view of a portion of the belt washer assembly of the belt filter press of FIG. 1 taken perpendicular to the longitudinal axis of the belt washer assembly.

[0012]FIG. 4 is a perspective view of a portion of the belt washer assembly of the belt filter press of FIG. 1 showing a washer spray head assembly.

DETAILED DESCRIPTION

[0013] Referring now to FIG. 1, a belt filter press 10 according to the invention comprises a frame 12, an upper belt 14, a lower belt 16, a waste placement apparatus 18, liquid catch pans 20, belt washers 22, a wedge section 24, a primary roller 26, secondary rollers 28, upper belt guide rollers 38, and lower belt guide rollers 32. It will be readily understood by one skilled in the art that the belt filter press of FIG. 1 will also comprise suitable belt tensioning devices, belt drives, and controls, which for purposes of this disclosure will not be described herein. As with a conventional belt filter press, the belt filter press 10 of FIG. 1 extrudes liquid from a mixture of solid and liquid material by “sandwiching” the mixture between the two belts 14, 16, in a compression zone, passing the belts over the wedge section 24 and around the primary and secondary rollers 26, 28, and discharging the dewatered solids upon separation of the belts 14, 16.

[0014] After the dewatered material has been expelled from the belt filter press, the belts are typically washed of any residual solid material adhering thereto. Adequate washing of the belts typically requires relatively large volumes of water, which must then be removed in order to avoid adding water to the mixture and reducing the efficiency of the dewatering process. Referring to FIGS. 2 and 3, a belt washer 22 according to the invention comprises a lower box 70, an upper box 72, and a washer assembly 76. The lower box 70 is an elongated container comprising two parallel ends 78, two parallel sides 80, and a bottom 90. Each end 78 terminates in an outwardly extending flange 82, provided with apertures 92 extending therethrough. The upper box 72 is an elongated container comprising two parallel ends 114, two parallel sides 116, and a top 150. Each end 114 of the upper box 72 terminates in an outwardly extending flange 118, provided with apertures 120 extending therethrough. The length of each box 70, 72 is generally equal to the width of the belts 14, 16.

[0015] The lower box 70 is provided with a pair of parallel outside wiper clips 84 and a pair of parallel inside wiper clips 86 extending longitudinally along the sides 80. Each parallel outside wiper clip 84 comprises a pair of parallel clip sides 94 and a clip bottom 96 defining a narrow channel slot 98. In the preferred embodiment, each clip 84 comprises a pair of narrow, elongated bars rigidly attached to the side 80 and extending along the length of the side 80. Each parallel inside wiper clips 86 comprises a pair of parallel clip sides 100 and a clip bottom 102 rigidly connected to define a narrow channel 104. In the preferred embodiment, each inside wiper clip 86 is rigidly attached to the ends 78 parallel to the outside wiper clips 84, preferably by welding. Channel braces 88 are regularly spaced along the clips 84, 86 and rigidly attach the inside wiper clips 86 to the outside wiper clips 84, such as by welding. Wipers 74 comprise flexible, elongated blades adapted to be slidably retained in the clips 84, 86, and to extend longitudinally from one end 78 to the other. Suitable materials for the wipers 74 include rubber and soft polyethylene.

[0016] Each side 116 of the upper box 72 terminates in a scraper edge 122. An inside scraper 124 comprises a rigid, narrow, elongated blade with a scraper edge 125. A pair of scrapers 124 is rigidly attached to the ends 114, such as by welding parallel to the sides 116 so that the edges 122, 125 define a fixed elevation. Scraper braces 126 are regularly spaced along the scrapers 122, 124 and rigidly attach the inside scrapers 124 to the sides 116, such as by welding, in order to eliminate lateral deflection of the inside scrapers 124. The lower flange apertures 92 and the upper flange apertures 120 are adapted to be in axial alignment when the upper box 72 and the lower box 70 are assembled into the washer 22. The alignment of the apertures 92, 120 enables the upper box 72 and the lower box 70 to be fixedly connected, such as by conventional bolted connections. The sides 116, the scrapers 124, and the clips 84, 86 are adapted so that, when the upper box 72 and the lower box 70 are assembled into the washer 22, the wipers 74 retained in the clips 84, 86 will extend toward the scrapers 122, 124, respectively, and the belts 14, 16 will be in contact with both the wipers 74 and the edges 122, 125.

[0017] One end 78, 114 of the lower box 70 and the upper box 72, respectively, is provided with a washer aperture 128 therethrough. The washer aperture 128 comprises a circular section 130 and a slot section 132. Proximate to the slot section 132 is a washer mounting aperture 134 adapted to receive and retain a threaded fastener, such as a machine screw. The other end 78, 114 is provided with a tube support 144 comprising a circular aperture therethrough.

[0018] Referring to FIG. 4, a washer assembly 76 comprises a washer tube 136 and a plurality of spray heads 138. The washer tube 136 comprises a hollow tube which is sealed at a distal end and provided with a suitable fitting 146 at a proximal end for connection to a water supply. The tube 136 is also provided with a mounting plate 140 adapted to extend over the slot section 132. The mounting plate 140 is rigidly attached to the tube 136, such as by welding, so that the plane of the plate 140 is orthogonal to the longitudinal axis of the tube 136. The plate 140 is provided with a mounting plate aperture 142. The spray heads 138 comprise generally circular projections extending longitudinally along the outer surface of the tube 136. Each spray head 138 is provided with a center aperture 139 adapted to disperse water in a spray pattern. The center aperture 139 is in fluid communication with the interior of the washer tube 136. Water supplied under pressure to the washer tube 136 will flow from the spray heads 138 in a dispersed pattern.

[0019] Each belt washer 22 comprises two washer spray head assemblies 76. One washer spray head assembly 76 is inserted into the lower box 70 and the other washer spray head assembly 76 is inserted into the upper box 72. The spray tube 136 is inserted through the washer aperture 128 by aligning the spray heads 138 with the slot section 132. The distal end of the spray tube 136 is inserted into the tube support 144. The mounting plate aperture 142 is aligned with the washer mounting aperture 134 and the washer spray head assembly 76 is secured to the boxes 70, 72 by use of a threaded fastener inserted therethrough. In the preferred embodiment, the spray heads 138 are aligned so that the spray is directed against the travel of the belt 14, 16. The lower box 70 is provided with a suitable drain 148 for removing the liquid from the washing process.

[0020] In use, the lower box 70 with installed washer spray head assembly 76 is mounted to the frame 12 through suitable connectors so that the belt 14, 16 is in contact with the wipers 74. The lower box 70 is oriented so that the longitudinal axis of the box 70 is orthogonal to the direction of travel of the belt 14, 16. The upper box 72 with installed washer spray head assembly 76 is attached to the lower box 70 by aligning the upper flange apertures 120 with the lower flange apertures 92 and inserting a threaded fastener, such as a bolt or machine screw, therethrough. The scrapers 122, 124 will be in contact with the belt 14, 16 to maintain the belt 14, 16 in contact with the wipers 74. The washer spray head assemblies 76 are connected to a pressurized water supply (not shown) and the drain 148 is connected to a suitable external drainage system (not shown). Water entering the washer spray head assemblies 76 will be sprayed from the spray heads 138 onto the belt 14, 16, removing residual cake from the belt 14, 16. The wash water will be removed from the belt 14, 16 by the wipers 74 and the edges 122, 125, and will be collected in the lower box 70 to be removed through the drain 148.

[0021] While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing description and drawings without departing from the spirit of the invention. 

1] in a belt filter press for deliquifying a material, of the type comprising two endless filter belts disposed adjacent each other so that a portion of the belts travel together and converge towards one another, the belts moving together in a compression zone wherein material between the belts is compressed so that liquid in the material is extracted from the material, and a belt washer for cleaning at least one of the belts of residual material, the improvement wherein: the belt washer has at least one wiper holder and at least one belt wiper, wherein the at least one belt wiper is disposed against a first surface of one of the belts and removably retained thereagainst by the at least one wiper holder. 2] The belt filter press of claim 1, wherein the at least one wiper holder is a clip. 3] The belt filter press of claim 2, wherein the at least one belt wiper is slidably retained in the clip. 4] The belt filter press of claim 1, wherein the at least one belt wiper is made of rubber. 5] The belt filter press of claim 1, wherein the at least one belt wiper is made of soft polyethylene. 6] The belt filter press of claim 1, wherein at least one scraper is disposed against a second surface of one of the belts opposite the at least one belt wiper. 7] The belt filter press of claim 6, wherein the at least one scraper presses the belt against the at least one belt wiper. 8] The belt filter press of claim 1, wherein the at least one belt wiper comprises a plurality of belt wipers, and wherein each belt wiper is disposed from the first belt wiper in the direction of belt travel. 9] The belt filter press of claim 8, wherein the belt washer is provided with a first pair of belt wipers and a second pair of belt wipers, with a sprayer disposed therebetween. 10] The belt filter press of claim 8, wherein the belt washer is provided with a plurality of scrapers equal to the number of belt wipers. 